1. Field of the Invention
The present invention relates to hinge assemblies used in foldable electronic devices, and particularly to a rotary type hinge assembly which enables a cover of a foldable electronic device to rotate while the rotary type hinge assembly is rotated with respect to a body of the foldable electronic device.
2. Prior Art
Portable electronic devices, such as mobile phones and PDAs (personal digital assistants), are becoming ever more popular along with the ongoing development of wireless communication technology and data processing technology. A large number of consumers favor a folder-type portable electronic device for its novelty, convenience and aesthetic appeal. The folder-type portable electronic device generally includes a cover, a body, and a hinge assembly rotatably interconnecting the cover and the body so that the cover can open or closed with respect to the body. The hinge assembly can generate a force, which acts on the cover in a direction which enables the cover to be fully opened when the cover has been manually rotated further than a predetermined angle. The hinge assembly can also generate a force which acts on the cover in a direction which forces the cover to be in tight contact with the body when the cover has been manually rotated less than a predetermined angle.
As mobile communication services gradually become more and more diversified, the functions of portable electronic devices are also rapidly diversifying. However, the conventional hinge assembly has the function of opening and closing the cover only along a single arcuate path with respect to the body. This limits the range of configurations that the portable electronic device may have. For example, additional devices can be added to the portable electronic device in only a limited number of locations. In another example, where a mobile phone includes a digital camera, the ability to take photos at various orientations of the mobile phone is limited. The hinge assembly cannot readily satisfy consumer preferences, and runs against the current trend toward providing various extra mobile communication services in portable electronic devices.
Recent inventions have attempted to solve the above-mentioned problems of the conventional hinge assembly.
For example, European patent application No. EP 1288414 A1, published under the name of inventors Kang, Sung-III et al and entitled “Rotary type hinge for portable wireless terminal” discloses a rotary type hinge assembly. This hinge assembly is represented in FIG. 9. The hinge assembly 100 includes a hinge body 110, a supporting shaft 130, a rotary shaft 170, a hinge cam 150, a driven element 160, and an elastic means 169. The hinge cam 150, the driven element 160 and the elastic means 169 are assembled with the supporting shaft 130 in that order, and received in the rotary shaft 170. The hinge body 110 has a holding pin hole 119a defined though one end thereof, and a hinge shaft hole (not shown) defined though the other end thereof. The hinge body 110 is rotatably assembled with the body of the portable electronic device at the holing pin hole 119a and the hinge shaft hole. The hinge body 110 includes a fixing seat 113a and an opening 111. The fixing seat 113a is formed at a middle portion of the hinge body 110, and the opening 111 is defined in the middle portion opposite from the fixing seat 113a. The supporting shaft 130 is fixed to the fixing seat 113a, and extends though the opening 111. The supporting shaft 130 has a step portion 133 and an annular groove 135. The supporting shaft 130 is received in the rotary shaft 170, and protrudes out through a shaft hole 173b so that the annular groove 135 is exposed. A fixing ring 181 is fitted in the annular groove 135. In particular, a washer 183 is fitted between the fixing ring 181 and the annular groove 135. The hinge cam 150 snugly receives the step portion 133, in order to be fixed on the supporting shaft 130. The hinge cam 150 has two distant valley-shaped portions 151 formed at one end thereof, and a curved surface formed between the valley-shaped portions 151. The driven element 160 is rotatably attached to the supporting shaft 130, and includes a mountain-shaped portion 161. The mountain-shaped portion 161 and the valley-shaped portion 151 are in sliding contact with each other.
This kind of rotary type hinge assembly enables the cover of the portable electronic device to rotate when the cover is flipped open with respect to the body of the portable electronic device. However, when the rotary shaft 170 rotates in order to drive the cover to rotate in unison, a thrust force is generated, which acts directly on the supporting shaft 130 at the annular groove 135. After repeated use, the supporting shaft 130 at the annular groove 135 is liable to fatigue and fracture. Additionally, the fixing ring 181 may loosen over time and make the mechanism unreliable. Furthermore, the engagement of the hinge cam 150 and the driven element 160 is such that the hinge assembly 100 can be stably located only at particular discrete angles such as 90 degrees or 180 degrees. When the cover has a display screen, he hinge assembly 100 does not allow the user to conveniently look at the screen from various different angles. Moreover, the configuration of the hinge assembly 100 is complicated, and it occupies a comparatively large volume.
Thus, a need exists for a new rotary type hinge assembly which overcomes the above-described shortcomings.